The proposed research is focused on detailed analyses of four critical components of mammalian meiosis: Cycle times; pachytene structure and pairing; sexual dimorphisms of diplotene and synaptinemal complex. Experiments with basic mechanisms of meiotic cycle times and durations and changes in chiasma formation with alterations in particular stages of prophase by external factors are detailed. Exploration of the nature of a pleiomorphic region discovered in mouse pachytene germ cells will be done. Identification of specific bivalents involved in pachytene non-homologous associations in oocytes is proposed. Testing of the hypothesis is that a sexual dimorphism pertains to individual chromosomes and the location/number of chiasmata will be done using diplotene germ cells. The fate of the synaptinemal complex will be studied through oogenesis to anaphase I.